In many cases the use of the same single pair of shoes can be necessary under many varying conditions. Even if the user knows what kind of terrain and weather conditions can be expected on the trail, it is often very inconvenient to carry several pairs of shoes. For example, at rock climbing or high altitude mountaineering, you can expect terrain with grass, mud, rock, snow and often ice. Presently used shoes with "universal" sole treads cannot meet all requirements. For example they are too high and too heavy for flat road surfaces, but do not provide good traction on icy surfaces.
Furthermore, the soles wear out faster than the upper part of the shoe. Commonly used methods of sole replacement are time consuming and expensive, usually necessitating the purchase of new shoes.
Shoes with easy to replace, removable outsoles can be very useful for tourists, as well as for workers when different surface conditions are expected or soles are worn out after a period of use. Use of this kind of shoe can be especially profitable for the armed forces because of their multi-purpose uses and low repair costs.
There are several different inventions related to shoes with replaceable outsoles. The prior art as best known to the inventor is represented by U.S. Pat. Nos. 3,538,628 (Einstein, 1970), 3,866,339 (Latto, 1975), 4,317,294 (Goodyear, 1982), 4,377,042 (Bauer, 1983), 4,606,139 (Silver, 1986), and 4,667,421 (Rouhani, 1970).
None of the above patents disclose the advantageous features of this invention, ie. really rapid, easy assembly and disassembly together with absolute security of the connection between the removable outsole and the upper portion of the shoe.